Subsurface irrigation of crops with water that contains dissolved oxygen and also micro-bubbles of air infused into the water by a mixer-injector, is shown in U.S. Pat. No. 6,173,526, issued to Angelo L. Mazzei, the inventor herein, on Jan. 16, 2001.
It is fundamental to growth of rooted plants, trees, and landscape that the roots have both water and oxygen. The customary source of oxygen is from air. Conventional growing procedures apply water to the surface of the ground. The water has some dissolved oxygen in it that is carried to the roots. This is usually insufficient, so the ground is permitted to dry in order to admit air into its structure which will be carried to the roots by the next irrigation or watering. This is a cyclic operation, and a farmer's profitability depends heavily on his applying enough water and air to accomplish this objective.
Too much water can literally drown the crop. Too little results in crop wilt and failure, or at least reduction in quality and production. Wastage of water is increasingly objectionable and expensive as water supply as a resource is diminished.
The system and process described in the said Mazzei patent improves the situation by supplying oxygen (usually from air) directly to the root zone without depending on seepage of water from the surface of the ground. Instead, water containing oxygen initially at a super-atmospheric pressure, and also air carried in micro-bubbles generated by passing the water through a mixer-injector, produces a surprisingly stable stream of water. Very small gas bubbles are injected into the soil along with the oxygen dissolved in the water.
This stream passes through a subsurface conduit. This conduit, often a drip irrigation tape or tube, (“tube” herein) is buried in the ground. In characteristic installations, this conduit extends for many yards, often along rows of crops such as strawberries and peppers. They discharge the water with its dissolved gases, and also with the entrained micro-bubbles of gas, usually air. Thus, both water in a correct amount and gas in a correct amount are released in the root zone where needed, and it is not necessary to flood the surface with its attendant evaporation and run-off wastage and other complications.
The system shown in the Mazzei patent has been in successful operation, producing significant increases in crop yield and quality. In some instances it has accelerated the maturity of the crop, enabling the grower to supply the early market. The early market commands a premium price.
It is customary to run an agricultural or landscape drip irrigation system to provide a reasonably filtered water and air (and additives if used), to supply the most troublesome parts of a field area. If some area shows problems of wilt, for example, the supply of the entire system is increased to be certain that all areas are sufficiently supplied. This means an oversupply to the regions which already would have had enough.
It is an object of this invention to improve the Mazzei system by providing for a more uniform distribution over the entire length of the conduitry, and to enable the discharge to occur in regions appropriate to the plants located there.
The micro-bubbles of gas are carried as a suspension in a flowing stream, and while the stream is flowing, there is some tendency for the gas to separate or coalesce, or for the fine unfiltered particles (“fines” herein) that may have passed through the filter to settle out. Reduced to absurdity, a stagnant stream would soon permit the mixed entrained air to coalesce, where it could cause uneven distribution or worse, result in a discharge as a flow of gas which will channel to the surface without diffusing along with the water. If the fines settle out in the tube, the tube must be flushed out periodically with water that will be wasted. The advantages of the gas are then mostly lost.
However stable the stream is, there will be a greater tendency for air to separate when the volume of micro-bubbles is highest. There is a tendency for air to be present in larger amounts upstream than downstream.
It is an object of this invention to provide conduitry in which the gas discharge “averages out” over the length of a plot.
It is another object of this invention to provide conduitry in a conveniently manufactured structure, and to provide for selective location of the related emitters and parts of the conduitry.
It is yet another feature of the invention to provide the micro-bubbles in a manner local to specific regions, rather than in a header where coalescing is likelier to occur.
It is another object of the invention to provide gases with other advantageous features such as fumigation.